GB2134851A

GB2134851A - Daisy-wheel printer

Info

Publication number: GB2134851A
Application number: GB08401169A
Authority: GB
Inventors: Ryuichi Okumura; Hidemi Dohi; Shingo Togawa
Original assignee: Tokyo Sanyo Electric Co Ltd; Tottori Sanyo Electric Co Ltd; Sanyo Electric Co Ltd
Current assignee: Tokyo Sanyo Electric Co Ltd; Sanyo Electric Co Ltd; Sanyo Consumer Electronics Co Ltd
Priority date: 1983-01-24
Filing date: 1984-01-17
Publication date: 1984-08-22
Also published as: DE3401823A1; DE3401823C2; US4541748A; GB2134851B; GB8401169D0

Description

1 GB 2 134 851 A 1

SPECIFICATION Printer

This invention relates to a printer which carries out printing by applying ink from an ink roller onto the type of a daisy wheel, and more particularly to a printer which controls the daisy wheel in the 70 rotation direction and the degree of rotation using a circumferential angle between the type to be printed and the ink roller.

Conventionally, a printer using a daisy wheel carries out printing by use of an ink ribbon. This method needs a drive mechanism for the ink ribbon and has a complicated construction. Hence, it has been proposed in Japanese Patent 15 Publication No. 4635, 1983, that an ink roller not needing the complicated drive mechanism is used 80 to apply ink on the type for printing. In this case, however, there is a problem in that the printing time varies corresponding to the set position of ink roller, whereby it is an important factor on the printing speed of printer where the ink roller is set. 85 In other words, in a case where an ink roller 1, as shown in Fig. 1 of the accompanying drawings, is set in a position at an angle of 1801 away from the printing position P on a daisy wheel 2 so that the type near the position P is to be printed, the daisy wheel 1 has to be rotated through about 3601 to bring the type firstly to the ink roller set position and secondly after being applied with ink, back to the printing position P. This is dis advantageous because of the long time taken from when a printing command is given to when the printing is performed. Also, in a case where the ink roller 1, as shown in Fig. 2, is set in a position at an angle of 901 on the circumference of daisy wheel 2 from the printing position P, in 100 order to print the type at about 1801 from the daisy wheel 2, the daisy wheel 2 has to be rotated through a maximum of 2701. Hence, the above Japanese Patent Publication No. 4635 discloses that, as shown in Fig. 3, two ink rollers 1, 1 are 1.05 set apart at an angle of 90' from the printing position P to increase the printing speed above that of Figs. 1 or 2, because the maximum rotary angle of daisy wheel 2 is 1801. But a such method cannot be said to be optimum since two ink rollers are required.

A first object of the invention is to provide a printer in which the ink roller is disposed at a suitable position on the circumference of daisy wheel at an angle of 901 or less from the printing position and which printer controls the daisy wheel in the rotation direction thereof and its rotary angle corresponding to the position of type to be printed, so that the printing speed is 120 improved.

A second object of the invention is to provide a printer which controls the rotation of daisy wheel to bring the type sufficiently into contact with the ink roller to thereby carry out exact and distinct printing.

A third object of the invention is to provide a printer which has practically attained the above objects by means of circuits which are simple in construction.

A fourth object of the invention or an embodiment thereof is to provide a printer which prevents the daisy wheel from being deformed and is free from printing nonuniformity.

Accordingly, the present invention provides a printer in which is disposed an ink roller in the rotation area of types of daisy wheel having radial fingers provided at the utmost ends thereof with said types, said ink roller being adapted to apply ink onto said types, wherein said ink roller is disposed in a position at an angle circumferentially of said daisy wheel of 901 or less from the printing position, and wherein a control circuit for rotation of said daisy wheel is provided, s t at when the type commanded to be printed is in a region between a first boundary position a number n of fingers away from the ink roller position and further round from the printing position and a second boundary position at an angle of 1801 or more from said first boundary position and further round from the printing position, said daisy wheel is rotated in such direction that said type goes toward the printing position via the ink roller position, thereby bringing said type to the printing position, and when the type commanded to be printed is outside of said region, said daisy wheel is rotated once in the direction reverse to the aforesaid direction so as to bring the type to said first boundary position and then rotated in the turning direction to bring said type in the printing position.

An embodiment of the invention is described, by example only in detail below, with reference to the accompanying drawings, wherein:

Figs. 1, 2 and 3 are views exemplary of the relationship between the daisy wheel and the ink roller of a conventional printer; Figs. 4, 5 and 6 are views exemplary of the relationship between a daisy wheel and an ink roller at a printer of the invention; Fig. 7 is a schematic side view of the printer of the invention; Fig. 8 is a schematic front view of the same; Fig. 9 is a block diagram of a control system for the printer of the invention; Fig. 10 is a flow chart of process contents for a control circuit of the printer of the invention and Fig. 11 is a view exemplary of the rotation direction of the daisy wheel.

In the printer of the invention, as shown in Fig. 4, an ink roller 1 is disposed in a position on the circumference of a daisy wheel 2 at a suitable angle 0 of 90' or less, for example, clockwise from the printing position P. The angle 0 forms a first boundary position. A second boundary position is set at a position at an angle of 180' around the circumference from the first boundary position. A semicircular portion not including printing position P is designated as a region 11, a portion between the printing position P and the first boundary position, i.e. in Fig. 4, the ink roller set position, as a region 1, and that portion 2 GB 2 134 851 A 2 between the printing position P and the secondary boundary position as a region 111. At the time of command of printing, the type to be printed if positioned in the region 11, is turned counterclockwise to the printing position P and passes through the ink roller 1 so as to be applied with ink; if the type to be printed is in the region I or III, it is turned clockwise once to the first boundary position i.e. here the ink roller 1 set position, and applied with ink and then turned counterclockwise toward the printing position P.

In addition, in the drawings, reference numerals 0, 1 and 99 designate code numbers attached to each type, i.e. each type code. In a case where the daisy wheel 2 is the printing standby condition to be discussed below and in the initial state, the type of code No. 0 is in the printing position P.

Fig. 5 shows a construction to apply ink from the ink roller 1 more reliably to the types, in which 85 the ink roller 1 is set at a position at a suitable angle 0 less than 9011 circurnferentially of daisy wheel 2 and for example, clockwise from the printing position P. A first boundary position is set several fingers away (at an angle a in Fig. 5) clockwise from the ink roller 1 set position, a second boundary position being set 1801 cir curnferentially of daisy wheel 2 away from the first boundary position. A semicircular portion not including the printing position P is designated by 95 region 11, a region from the printing position P to the first boundary position, in other words the position at an angle O+a circurnferentially clock wise of daisy wheel 2, as a region I and a portion from the printing position P counterclockwise toward the second boundary position as a region 111. The types positioned between the ink roller 1 set position and the printing position P in the region I and those in the region III, are first turned clockwise toward the first boundary position and, 105 after passing through the ink roller 1 so as to be applied with ink, then turned counterclockwise to the printing position P. The types positioned in the region 11 are turned counterclockwise toward the printing position P, on the way passing through the ink roller 1 and being applied with ink. In this case, the types positioned between the ink roller 1 set position within the region I and the first boundary position are turned once clockwise to the first boundary position and then counter clockwise toward the printing position P, thereby causing a little time to be wasted.

In Fig. 6, a construction to save the above mentioned time is shown in which the ink roller 1 is disposed at a position at a moderate angle 0 120 less than 900, for example, clockwise circum ferentially of the daisy wheel 2 from the printing position P, the position at angle 0 being defined as the first boundary position. The second boundary position is defined at the position at an 125 angle of 1800 from a position apart by the width of several fingers (the angle a in Fig. 5) cir curnferentially clockwise of daisy wheel 2 from the first boundary position. A portion not including the printing position P and of an angle of 1800 +a circumferentially of daisy wheel 2 between the first and second boundary positions is designated by region II. A portion between the printing position P and the first boundary position, i.e. the ink roller 1 set position, is designated by a region 1, and that between the printing position P and the second boundary position by a region 111. Thus, the types positioned in the regions I and III are once turned clockwise and pass through the ink roller 1 set position and are turned further by an angle a so as to be applied with ink and thereafter turned counterclockwise toward the printing position P. The types in the region 11 are turned counterclockwise toward the printing position P, on the way being applied with ink by the ink roller 1.

In an embodiment of the invention to be discussed below, the aforesaid first boundary position, that is the ink roller 1 set position, as shown in Fig. 6, corresponds to the 1 7th of 100 fingers clockwise from the printing position P, the second boundary position corresponds to the 70th finger, an angle of 10.80 corresponding to three fingers is represented by a, and an angle of 61.2 0 corresponding to seventeen fingers is represented by 0 between the printing P and the ink roller 1 set position.

The printer of an embodiment of the invention provides short fingers at the daisy wheel 2 so that when the daisy wheel 2 is in the initial position and in the standby condition, the short fingers opposite the ink roller 1 in the ink roller 1 set position, thereby preventing the daisy wheel 2 from being deformed due to contact of types with J 00 the ink roller 1 over a long period of time.

Fig. 7 is a schematic side view of the printer of the invention, and Fig. 8 is a schematic front view of the same, in which reference numeral 6 designates a carriage supported slidably on guide shafts 7, 7 fixed to a frame 10. The carriage 6 can be moved by a moving mechanism (not shown). On the carriage 6 are disposed the daisy wheel 2 provided radially with fingers each having at the utmost end thereof a type, a pulse motor 3 for rotating the daisy wheel 2, a hammer 4 for striking the type at each finger, and a plunger 5. The frame 10 supports a platen 8, on which a paper 9 is wound.

The ink roller 1, when the carriage 6 is moved, does not contact the platen 8 and others and is disposed at a position at an angle of 901 or less around the circumference of daisy wheel 2 from the printing position P. For this embodiment, at the position of the 1 7th finger of the 100 fingers of the daisy wheel 2 and clockwise from the printing position P, i.e. at an angle of 61.21, the ink roller 1 comes into contact with the types of daisy wheel 2 following the rotation thereof, thereby applying ink to the types.

The daisy wheel 2 as abovementioned is provided with 100 radially extending fingers, the types formed at the utmost end of each finger having type codes of from No. 0 to 99 to be discussed below. The state where the type of type code 0 is in the printing position P is called the 4 3 GB 2 134 851 A 3 initial position of daisy wheel 2. In this embodiment, a portion of the 100 fingers of the daisy wheel 2 at the ink roller 1, namely three fingers comprising the finger of code No. 17 and those at each side thereof, when the daisy wheel 2 is in the initial position, are smaller in length, thereby forming a cutout 11, as shown in Fig. 8. Thus, when the daisy wheel 2 is kept in the initial position, the ink roller 1 does not contact the type.

For carrying out printing, the paper 9 is wound onto the platen 8, and then the pulse motor 3 is driven to rotate the daisy wheel 2 and bring a desired type to the printing position P. At this time, since ink is applied on the type due to contact with the ink roller 1 following the rotation 80 of daisy wheel 2, the plunger 5 is energized to drive the hammer 4, whereby a desired type is struck and thereby printing on the paper 9. Then, the carriage moving mechanism (not shown) moves the carriage 6 to the next printing position, standing by for the subsequent printing. If the next printing is not carried out within the pre determined time as described below, the daisy wheel 2 will restore to the initial position.

Fig. 9 is a block diagram of a control system for the printer of the invention, in which reference numeral 20 designates a keyboard provided with numeric keys, alphabet keys, and various specific symbol keys or the like. When the keyboard 20 is operated to select the character to be printed, a key signal corresponding to the selected key and a printing signal for commanding the printing are given to a control circuit 2 1.

The control circuit 21 comprises a micro- processor, and when given the key signal and printing signal from the keyboard 20, controls according to a program stored in a program memory 22 a printing mechanism 23 comprising the pulse motor 3, plunger 5, carriage 6, etc. The printing mechanism 23 is given from the control circuit 21 a pulse signal S1 for driving the pulse motor 3, a drive signal S 2 for the plunger 5, and a drive signal S 3 for the carriage 6. The printing mechanism 23, when the daisy wheel 2 is put into the initial position, gives to the control circuit 110 2 1, as an initial position signal S4. the original pulse from the pulse motor 3 or a rotary encoder (not shown) connected to the daisy wheel 2.

In the drawing, reference numeral 24 designates a type code memory storing therein 115 the code number corresponding to each type in order to identify each type of daisy wheel 2 corresponding to the key signal given from the keyboard 20. In this embodiment the daisy wheel 2 has 100 radially extending fingers as shown in Fig. 8. In a case where the daisy wheel 2 is set in the initial position, three fingers opposite to the ink roller 1 are not provided with the types, but form a cutout 11. The other 97 fingers are provided with the types at the outermost end thereof. The types are numbered 0 to 99 (except for the 1 6th, 1 7th and 18th) as code numbers, for example No. 10 corresponding to letter "A", which are stored in the type code memory 24, the type code corresponding to the key signal given from the keyboard 20 operated being retrieved by the control circuit 21 and read therein.

A first counter 25 counts the degree of rotation of daisy wheel 2 from the initial position and comprises a centesimal up/down counter. In other words, the first counter 25 uses as the clock pulse CP the pulse driving the pulse motor 3 to rotate the daisy wheel 2, and uses as the up/down signal U/D the signal indicating the normal or reverse rotation of daisy wheel 2, thereby carrying out the up-count when the daisy wheel 2 rotates clockwise and the down-count when the same rotates counterclockwise. When the count advances to 99 at the up-counting, 0 is sequentially counted. When the down-count advances to 0, 99 is sequentially counted. Furthermore, where the daisy wheel 2 returns to the initial position and the initial position signal S4 is given from the printing mechanism 23 to the control circuit 2 1, the first counter 25 is given a reset signal R from the control circuit 21 to reset it. A counting value C1 of the first counter 25, as discussed below, is read as the data for rotation control of daisy wheel 2 into the control circuit 21 at each time the printing signal is given thereto.

A second counter 26 comprises a down counter which is so constructed that data D2 sent from the control circuit 21 is preset at the time when the second counter 26 is given a preset enable signal PE from the control circuit 21, so that the pulse to drive the pulse motor 3 is counted down as the clock pulse CP from the value of preset data D2. At the time when the down-count value C2 reaches zero, the second J 00 counter 26 gives a signal S. to the control circuit 2 1, thereby stopping. a pulse input given to the pulse motor 3 to drive it.

A pulse generating circuit 27 generates a pulse for driving the pulse motor 3, the generated pulse signal is converted by the control circuit 21 into the signal corresponding to the rotation directioh of daisy wheel 2 and given properly to the pulse motor 3 to rotationally drive it and also given as the clock pulse CP to the first and second counters 25 and 26.

Next, explanation will be given to the operation of the above printer in accordance with the flow chart of Fig. 10 and with Fig, 11 showing the rotation direction of daisy wheel 2.

In this embodiment, as abovementioned, the situation where the type of code number 0 is in the printing position P as shown in Fig. 11 -(a), is called the initial position of daisy wheel 2, the ink roller 1 is disposed at the position of the 1 7th finger clockwise from the printing position P, the first boundary position for defining the rotation direction of daisy wheel 2 is the ink roller 1 set position, and the position of the 70th finger part from the ink roller 1 set position by an angle of 1800 +a (a: an angle corresponding to the width of three fingers) is the second boundary position. One of the two portions divided by the first and second boundary positions and not including the printing position P is designated by region 11, a portion between the printing position P and the 4 GB 2 134 851 A 4 first boundary position, i.e. the ink roller 1 set position, is designated by region 1, and a portion between the printing position P and the second boundary position is designated by region Ill. The types positioned within the regions 1 and Ill are first turned clockwise to the position of an angle of 0+aO from the printing position P, i.e. the position of the 20th finger, and thereafter turned counterclockwise to a position at the printing l 0 position P.

Firstly, explanation will be given to the operation of printing where the daisy wheel 2 is stationary at its initial position. In the case where the letters of code number up to No. 15 (Nos. 16 and 17 are cut out), in other words the types positioned in the region 1, are printed, the control circuit 2 1, when given the print signal and key signals from the keyboard 20, reads from the type code memory 24 the corresponding type code on the basis of key signal given from the keyboard 20 and also reads the count value Cl of first counter 25, thereby performing computation of "N=Type code+First counter value C 1 ", where since the daisy wheel 2 is in the initial position, the count value Cl of first counter 25 is zero and the computation result -N- is equal to the value of the type code. Hence, for example, when the type of code number 10 is selected, the computation result is---N=1 W. Continuously, the control circuit 21 decides whether or not the computation result "N" is larger than 1110011, because---Wmore than ---100---means one rotation of daisy wheel 2 and numerals in the 100 order are meaningless in the actual computation. Now, in this case, since -N- is---10---and smaller than---100-, in order to decide whether or not the type selected is positioned at present within the region I I I, it is decided whether or not "N" is larger than---70---. Now, since "N" is " 10--and smaller than---70-, in order to decide whether or not the type selected is positioned at present in the region 1, it is decided whether or not -N- is smaller than---17---. Since the computation result "N" is---1 W and smaller than ---17-, in order to obtained data D2 necessary to rotate the selected type from the printing position P clockwise toward the position of 20th finger, ---20-N- is computed. Since the preset enable signal PE is given to the second counter 26, the computation result---1 W' is preset as the data D2 to the second counter 26. Sequentially, the control circuit 21 generates a signal for rotating clockwise the pulse motor 3 at the printing mechanism 23, thereby driving the pulse motor 3 by the pulse and rotating the daisy wheel 2 clockwise (see Fig. 11 -(b)). The pulse for driving the pulse motor 3 is given as the clock pulse CP to the second counter 26, the second counter 26 counting down one by one per one pulse, so that when 10 pulses are given, the count value C2 becomes "0", whereby the signal S5 is given to the control circuit 2 1. Hence, the pulse input to the pulse motor 3 is stopped to stop the rotation of daisy wheel 2.

The clockwise rotation of daisy wheel 2 makes the type of code No. 10 rotate clockwise to the position of the 20th finger from the printing position P; on the way the ink roller 1 applies ink to the type of code No. 10. Simultaneously with the above, the first counter 25 is given the pulse as the clock pulse CP to rotate the pulse motor 3 clockwise, and counts up the count value Cl only by "l 0". Continuously, the control circuit 21 gives the preset enable signal PE to the second counter 26, data "20" for rotating the type at the position of 20th finger toward the printing position P is preset in the second counter 26 so that the pulse is given to rotate the pulse motor 3 counterclockwise, and the daisy wheel 2 is rotated counterclockwise until the second counter 26 counts down to "0". At the time of down-count of the second counter 26 to "0", the generation of pulse signal from the control circuit 21 stops to stop the rotation of daisy wheel 2, whereby the type of code No. 10 to be printed is positioned at the printing position P. Then, the control circuit 21 gives a plunger driving signal S2 to the printing mechanism 23 to thereby energize the plunger 5, by which the hammer 4 is driven to strike against the platen 8 the type of code No. 10 positioned at the printing position P. At this time, the first counter 25 counts down by "20" its count value C 1 due to the pulse for rotating the pulse motor 3 counterclockwise, so that the count value Cl exceeds "0" to be "90", which shows that the type of code No. 0 transfers clockwise from the printing position P to the position of the 90th finger.

Next, explanation will be given to the case where the type of code No. 50 positioned in the region 11 is printed when the daisy wheel 2 is in the initial position. In this case, as in the former case, in order that the computation result "N" becomes "50" after the step of deciding the region, the type of code No. 50 is discerned to be in the region 11, "50" as data D2 necessary to rotate the above type to the printing position P is preset in the second counter 26, and sequentially the pulse to rotate the pulse motor 3 counterclockwise is generated, so that the daisy wheel is rotated counterclockwise until the down count value of the second counter 26 becomes "0". After having generated 50 pulses, the count value C2 of the second counter 26 is "0", resulting in the type of code No. 50 being in the printing position P (see Fig. 11 -(c)), at which time the type of code No. 50 comes into contact with the ink roller 1 during rotation toward the printing position P, thereby being applied with ink. Accordingly, at this time, if the hammer 4 is driven, the type of code No. 50 is printed. At this time, the count value Cl of first counter 25 is counted down from "0" and exceeds "99" to be 1150".

Next, explanation will be given to the case wherethetypesof codes Nos. 79to 99 and in the region Ill are printed when the daisy wheel 2 is in the initial position. For example, the type of code No. 80 is assumed to be selected by the keyboard 20. After the step of deciding the region in which GB 2 134 851 A 5 the type actually exists as in the former case, the computation result "N" is "80", i.e. more than "70", thereby deciding the types existence in the region Ill. Next, in order to obtain data D2 necessary to rotate the selected type from the printing position P to the position of the 20th finger, " 1 00-N+20" is computed and the computation result "40" is preset as the data D2 in the second counter 26. Continuously, the control circuit 21 generates a pulse for rotating the pulse motor 3 clockwise to thereby rotate the daisy wheel 2 clockwise until the count value C2 of second counter 26 is counted down to "0". In this case, the second counter 26 has preset "40" so that at the time of having generated 40 pulses, in other words after the type of code No. 80 contacts the ink roller 1, and further at the time of having rotated to an extent of three fingers clockwise to the position of 20th finger from the printing position, the pulse generation is stopped to stop the rotation of daisy wheel 2. Continuously, the control circuit 21 presets data "20" in the second counter 26 and generates a pulse to rotate the pulse motor 3 counterclockwise, thus rotating the daisy wheel 2 counterclockwise. When the pulse motor 3 is given 20 pulses so that the count value C2 of second counter 26 becomes "0", the generation of pulses stops and the daisy wheel 2 stops its rotation to thereby put the type of code No. 80 in the printing position P. Hence, at this time, the hammer 4, when driven, makes the type of code No. 80 print (see Fig. 11 -(d)), at which time the first counter 25 counts up only by "40" due to the clockwise rotation of pulse motor 3, and thereafter counts down due to the counterclockwise rotation of the same, the count value Cl being "20".

Next, explanation will be given to a continuous printing operation, for example the operation of printing the type of code No. 50 in continuation after the type of code No. 10 is printed when the daisy wheel 2 is put in the initial position. In this case, after the type of code No. 10 is printed as explained above when the key signal corresponding to the type of code 50 is given to the control circuit 21 from the keyboard 20, the control circuit 21 reads the corresponding type code "50" from the type code memory 24 and fetches the count value Cl: "90" from the first counter 25, thereby adding both the data. Then the control circuit 21 enters the decision step of computation result "N", in which the computation result "l 40" is larger than "l 00", whereby the control circuit 21 enters the computation step of " 140-100" and sequentially enters the decision step of substraction result "40". Now, since "40" is larger than " 17", the type of code No. 50 is determined to be at present in the region 11 and the data "40" is preset in the second counter 26, and thereafter the pulse for counterclockwise rotating the pulse motor 3 is generated to rotate the daisy wheel 2 counterclockwise. The daisy wheel 2 continues its rotation by 40 pulses until the second counter 26 counts down to "0" (see Fig. 11 -(e)). Hence, when the count value C2 of second counter 26 is -0-, the type of code No. 50 is put in the printing position P and printed by the driving of the hammer 4, at which time the count value Cl of first counter 25 is counted down to "50---because of count-down by---40" from---90---.

In a case where, for example, the type of code No. 40 is printed in continuation, since the computation result "N" is "90" as abovementioned, it is decided that the type of code No.

40 is in the region Ill. Hence "100-90+20" is computated, the pulse motor 3 is rotated clockwise only by "30-, ink is applied onto the type, and the pulse motor 3 is rotated counterclockwise by 20 pulses, so that the type of code No. 40 is put in the printing position P to be printed (see Fig. 11 -(f)). Thus, even when the key input is given in continuation, thecomputation process is carried out on the basis of numeral values of type code and the count value Cl of first counter 25 so that the rotation direction and rotary angle of daisy wheel 2 are controlled on the basis of the computation result, thereby allowing continuous printing in a short time.

in addition, if the key is not given in continuation for more than the predetermined time period, the control circuit 21 decides the count value Cl of first counter 25. If it is "ll " to ---50-, the daisy wheel 2 is rotated counterclockwise, and if---51 " to "99---clockwise, so that the daisy wheel 2 is restored to the initial position. When the initial position signal S4'S generated by the restoration of daisy wheel 2, the control circuit 21 resets the first counter 25. Therefore, the cutout 11 of 3 fingers at the daisy wheel 2 is put at the ink roller 1 set position to thereby avoid redundant contact of the type with the daisy wheel 2, thus preventing the daisy wheel 2 from being deformed.

As seen from the above, the printer of the invention controls the daisy wheel in the rotation direction by a distance between the ink roller and the type to be printed, in other words the circumferential angle of daisy wheel, thereby improving the printing speed. Also, in a case where the type once passes through the printing position and then rotates reversely to the ink roller set position, this printer is so constructed that the type passes through the ink roller set position in a width of several fingers and thereafter is rotated in the reverse direction to be put in the printing position, thereby enabling exact application of ink for the types to provide an improvement in printing quality.

Furthermore, the printer of this embodiment of the invention, in the stand by condition of the daisy wheel, puts the cutout of the fingers in the ink roller set position, whereby there is no danger of deformation of the daisy wheel, and the prevention of nonuniformity in print is possible.

Alternatively, the ink roller in this embodiment may be provided within an angle of 901 counter clockwise from the printing position. In this case, the daisy wheel need only be made reversely rotatable.

6 GB 2 134 851 A 6

Claims

1. A printer in which is disposed an ink roller in the rotation area of types of a daisy wheel having radial fingers provided at the utmost ends thereof with said types, said ink roller being adapted to apply ink into said types, wherein said ink roller is disposed in a position at an angle cir cumferentially of said daisy wheel of 901 or less from the printing position, and wherein a control circuit for rotation of said daisy wheel is provided, so that when the type commanded to be printed is in a region between a first boundary position number n of fingers away from the ink roller position and further round from the printing 50 position and a secondary boundary position at an angle of 1801 or more from said first boundary position and further round from the printing position, said daisy wheel is rotated in such direction that said type goes toward the printing position via the ink roller position, thereby bringing said type to the printing position, and when the type commanded to be printed is outside of said region, said daisy wheel is rotated once in the direction reverse to the aforesaid direction so as to bring the type to said first boundary position and then rotated in the turning direction to bring said type in the printing position.

2. A printer as set forth in Claim 1, wherein 65 said number n of fingers is zero.

3. A printer as set forth in Claim 1, wherein said number n of fingers is one or two or more.

4. A printer as set forth in any preceding claim, wherein said second boundary position is at an angle of 1801 from said first boundary position and further round from the printing position.

5. A printer as set forth in any of claims 1 to 3, wherein said second boundary position is apart from said first boundary position by an angle of 1801 plus an angle corresponding to a plurality of said fingers, further around from the printing position.

6. A printer as set forth in any preceding claim wherein fingers positioned at a portion of said daisy wheel corresponding to the ink roller set position when said daisy wheel is in a printing stand-by condition are smaller in length than the other fingers so as not to come into contact with said ink roller.

7. A printer as set forth in any preceding claim, wherein said control circuit comprises:

a first counter having a counting content corresponding to the rotational position of said daisywheel, means to compute the sum of said counting content of said first counter and a code corresponding to a type commanded to be printed, means to determine on the basis of said sum which region includes the type commanded to be printed, means to decide on the basis of said determined region the rotation direction and degree of rotation of said daisy wheel, and a second counter by which a numerical value corresponding to said degree of rotation is preset and counted down following rotation of said daisy wheel.

8. A printer substantially as herein described with reference to any of Figs. 4 to 11 of the accompanying drawings.

Printed for Her Majesty's Stationery Office by the courier Press, Leamington Spa, 1984. Published by the Patent Office, 25 Southampton Buildings, London, WC2A 1 AY, from which copies may be obtained.

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